U.S. patent application number 10/282923 was filed with the patent office on 2003-09-11 for programmable surface control devices and method of making same.
Invention is credited to Kozicki, Michael N..
Application Number | 20030168651 10/282923 |
Document ID | / |
Family ID | 23329789 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030168651 |
Kind Code |
A1 |
Kozicki, Michael N. |
September 11, 2003 |
Programmable surface control devices and method of making same
Abstract
Programmable surface control devices whose physical features,
such as surface characteristics and mass distribution, are
controlled by the presence or absence of an electrodeposition of
metal and/or metal ions from a solid solution upon application of a
suitable electric field.
Inventors: |
Kozicki, Michael N.;
(Phoenix, AZ) |
Correspondence
Address: |
Snell & Wilmer LLP
One Arizona Center
400 East Van Buren
Phoenix
AZ
85004-2202
US
|
Family ID: |
23329789 |
Appl. No.: |
10/282923 |
Filed: |
October 28, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60339604 |
Oct 26, 2001 |
|
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Current U.S.
Class: |
257/2 ; 257/4;
257/5; 257/E27.004; 257/E45.002 |
Current CPC
Class: |
H01L 45/1266 20130101;
H01L 45/1226 20130101; H01L 45/085 20130101; H03H 3/0077 20130101;
H03H 9/2457 20130101 |
Class at
Publication: |
257/2 ; 257/4;
257/5 |
International
Class: |
H01L 047/00 |
Claims
I claim:
1. A programmable surface control device comprising: a solid
electrolyte solution layer containing a conductive material; and a
pair of electrodes positioned on a surface of said solid
electrolyte solution layer wherein one of said electrodes includes
said conductive material wherein the solid electrolyte solution and
the electrodes are configured to alter a surface property of the
device.
2. The programmable surface control device of claim 1, wherein said
solid electrolyte solution layer comprises a chalcogenide glass and
said conductive material comprises a metal dissolved within said
chalcogenide glass.
3. The programmable surface control device of claim 2, wherein said
metal is selected from the group consisting of silver, copper, and
zinc.
4. The programmable surface control device of claim 2, wherein said
chalcogenide glass is selected from the group consisting of
As.sub.xS.sub.1-x, Ge.sub.xS.sub.1-x and Ge.sub.xSe.sub.1-x.
5. The programmable surface control device of claim 1, wherein said
pair of electrodes include an anode having an oxidizable form of
said conductive material and an inert cathode.
6. The programmable surface control device of claim 1, further
comprising an electrodeposit on a surface of said solid electrolyte
solution layer extending between said pair of electrodes.
7. The programmable surface control device of claim 6, wherein said
electrodeposit causes a surface of said solid electrolyte solution
layer to be hydrophobic.
8. The programmable surface control device of claim 6, wherein said
electrodeposit causes an increase in friction of a surface of said
solid electrolyte solution layer.
9. A material surface comprising a plurality of programmable
surface control devices as defined in claim 1 wherein said material
surface comprises said solid electrolyte solution layer.
10. The material surface of claim 9, wherein at least one of said
programmable surface control devices further comprises an
electrodeposit.
11. The material surface of claim 9. wherein said material surface
is a hydrophobic surface and said programmable surface control
devices are organized individually on said hydrophobic surface.
12. The material surface of claim 9, wherein said material surface
is a hydrophobic surface and said programmable surface control
devices are organized in arrays.
13. The programmable surface control device of claim 1, wherein
said device is disposed in walls of a microchannel.
14. The programmable surface control device of claim 13 further
comprising an electrodeposit which changes a contact angle at a
wall of said microchannel thereby creating a liquid valving
effect.
15. The programmable surface control device of claim 1 further
comprising a liquid droplet disposed on the surface of said solid
electrolyte solution layer.
16. The programmable surface control device of claim 15, wherein
said liquid droplet comprises a water droplet and said solid
electrolyte solution layer comprises a chalcogenide glass with a
dissolved metal.
17. The programmable surface control device of claim 16 further
comprising an electrodeposit on the surface of said solid
electrolyte solution layer to shape the water droplet.
18. The programmable surface control device of claim 17 further
comprising a polymer film applied to the water droplet.
19. A continually renewable metallized surface comprising: a solid
electrolyte solution layer containing a conductive material; a pair
of electrodes positioned on a surface of said solid electrolyte
solution layer wherein one of said electrodes includes said
conductive material; an electrodeposit on a surface of said solid
electrolyte solution layer extending between said pair of
electrodes; and a sufficient bias between said pair of electrodes
to effectively renew said electrodeposit and compensate for wear of
said electrodeposit.
20. A method for forming a programmable surface control device
comprising the steps of: forming a solid electrolyte solution layer
containing a conductive material; and forming a pair of electrodes
on a surface of said solid electrolyte solution layer wherein one
of said electrodes includes said conductive material, said
electrolyte solution layer and said electrodes being configured to
alter a surface property of the device upon applying a voltage to
the electrodes.
21. The method of claim 20 further comprising the step of applying
a voltage between said pair of electrodes to form an
electrodeposit.
22. The method of claim 21, wherein the step of applying a voltage
comprises applying a voltage within a range of about 200 mV to
20V.
23. The method of claim 21, wherein the step of applying a voltage
comprises forming an electrodeposit that extends between said pair
of electrodes across the surface of the solid electrolyte solution
layer.
24. The method of claim 20, wherein said step of forming a solid
electrolyte solution layer comprises the step of forming a
chalcogenide glass with a dissolved metal.
25. The method of claim 24, wherein said step of forming a pair of
electrodes comprises the step of forming an anode having an
oxidizable form of the metal dissolved in the chalcogenide glass
and an inert cathode.
26. The method of claim 21, wherein said electrodeposit alters a
surface tension of said solid electrolyte solution layer thereby
increasing an angle at which the electrodeposit contacts the
layer's surface resulting in a more hydrophobic surface.
27. The method of claim 21, wherein said electrodeposit increases
friction of the surface of said solid electrolyte solution
layer.
28. The method of claim 20, wherein said steps are repeated to form
a plurality of programmable surface control devices on the surface
of said electrolyte solution layer.
29. The method of claim 28 further comprising the step of applying
a voltage to at least one pair of electrodes to control
distribution of a liquid on the surface of said electrolyte
solution layer.
30. The method of claim 20, wherein said programmable surface
control device is formed within walls of a microchannel.
31. The method of claim 20 further comprising the step of disposing
at least one liquid droplet on the surface of said electrolyte
solution layer to form a liquid microlens.
32. The method of claim 31 further comprising the step of applying
a voltage to said pair of electrodes to control at least one of a
shape and a focal point of said liquid microlens.
33. The method of claim 32 further comprising the step of applying
a polymer film to the liquid droplet to prevent its
evaporation.
34. A method for controlling the friction of a surface used to
operate a MEMS component comprising the steps of: forming a solid
electrolyte solution layer containing a conductive material;
forming a pair of electrodes on a surface of said solid electrolyte
solution layer wherein one of said electrodes includes said
conductive material; and applying a voltage between said pair of
electrodes to form an electrodeposit on the surface of said
electrolyte solution layer between said electrodes.
35. A method for continually renewing a metallized surface
comprising the steps of: forming a solid electrolyte solution layer
containing a conductive material; forming a pair of electrodes on a
surface of said solid electrolyte solution layer wherein one of
said electrodes includes said conductive material; applying a
voltage between said pair of electrodes to form an electrodeposit
on the surface of said electrolyte solution layer between said
electrodes; and maintaining a sufficient bias between said pair of
electrodes to effectively renew to effectively renew said
electrodeposit and compensate for any wear of said electrodeposit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Serial No. 60/339,604, filed Oct. 26, 2001 which is
herein incorporated by reference.
FIELD OF INVENTION
[0002] The present invention generally relates to programmable
surface control devices, and more particularly to programmable
microelectronic surface control devices that utilize
microelectronic structures in combination with an electrochemical
reaction to control such devices.
BACKGROUND OF THE INVENTION
[0003] Programmable Metallization Cell (PMC) technology is
generally based on the electrodeposition of metal and/or metal ions
from a solid solution upon application of a suitable field. The
programmable metallization cell disclosed in U.S. patent
application Ser. No. 09/502,915, filed Feb. 11, 2000, which is
herein incorporated by reference, is a structure that operates very
effectively as a non-volatile memory device. The mechanism for the
memory device utilizes a thin amorphous material with two metal
contacts where the amorphous material can incorporate relatively
large amounts of metal to behave as a solid electrolyte. Under
certain bias conditions, the metal ions in the electrolyte are
reduced to form an electrodeposit that acts as a conducting link
between the metal contacts (electrodes). As a result, the
resistance of the device can be greatly decreased. In addition,
applying a reverse bias will cause the electrodeposit to disperse
and return the device to a state of high resistance.
[0004] Formation or dissolution of an electrodeposit on a
microelectronic structure or device changes the surface
characteristics of the device thereby enabling one to manipulate or
control the surface of the device. Moreover, since the ability to
increase applications of a device depends on the ability to
manipulate or control the device, there is a need for devices which
already possess the ability to control surface characteristics and
mass distributions of the devices by simply applying electrical
means to the devices.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to surface structures of
microdevices whose physical and electrical features can be
manipulated by applying an electrical means to the structures in
order to control the surface characteristics and mass distribution
of such devices. Applying an electrical means to microdevice
structures having certain compositions will cause the
electrodeposition or electrodissolution of an electrodeposit which
can significantly alter the surface characteristics and mass
distribution of the microdevice.
[0006] In accordance with one exemplary embodiment of the present
invention, a programmable surface control device includes a solid
electrolyte solution layer containing a conductive material, and a
pair of electrodes on the surface of the electrolyte solution layer
with one of the electrodes having the same type of conductive
material as the electrolyte solution layer. In accordance with one
aspect of this exemplary embodiment, the electrolyte solution layer
is a chalcogenide glass with a dissolved metal such as silver,
copper, and zinc. Exemplary chalcogenide glasses with dissolved
metal in accordance with the invention include solid solutions of
As.sub.xS.sub.1-x--Ag, Ge.sub.xSe.sub.1-x--Ag,
Ge.sub.xS.sub.1-x--Ag, As.sub.xS.sub.1-x--Cu,
Ge.sub.xSe.sub.1-x--Cu, Ge.sub.xSe.sub.1-x--Cu, combinations of
these materials, and the like. In accordance with another aspect of
this embodiment, an electrodeposit is present on the surface of the
solid electrolyte solution layer extending between the pair of
electrodes. The electrodeposit causes the surface of the solid
electrolyte solution layer to become hydrophobic and can also cause
an increase in friction of the surface layer.
[0007] In accordance with another exemplary embodiment of the
present invention, multiple programmable surface control devices as
described above may be present on a material surface layer such as
the solid electrolyte solution layer in order to control fluid
distribution of small quantities of fluids on surfaces, such as the
formation of droplets. The devices can be organized individually to
trap single droplets or in arrays to form multiple controllable
sample sites. In accordance with another aspect of the exemplary
embodiment of the present invention, the programmable surface
control devices may comprise various geometries and may further act
as tension dams to control fluid distribution.
[0008] In accordance with still another exemplary embodiment of the
present invention, a programmable surface control device like that
described above is disposed in the walls of a microchannel to
control fluid flow in a microfluidic system. In this exemplary
embodiment, an electrodeposit is formed between the electrodes to
change the contact angle of the fluid at the wall of the
microchannel where an increase in the contact angle can function to
restrain fluid flow. Moreover, applying a reverse bias between the
electrodes will cause the electrodissolution of the electrodeposit
which will decrease the contact angle of the fluid at the wall
thereby increasing fluid flow.
[0009] In accordance with yet another exemplary embodiment of the
present invention, a programmable surface control device like that
described above may further comprise a liquid droplet to create a
liquid microlens that can be used for temporary imaging and/or
focusing/coupling applications. The shape and focal length of the
microlens can be controlled by the formation or dissolution of an
electrodeposit on the surface of the solid electrolyte solution
layer which functions to change the contact angle of liquid
droplets that are disposed on the solid electrolyte solution layer.
Further, in one aspect of this exemplary embodiment of the device,
a polymer film that does not adversely affect the desired focal
length of the liquid droplets may be applied to the liquid droplets
to prevent their evaporation.
[0010] In accordance with another exemplary embodiment of the
present invention, a programmable surface control device like that
described above may be used to control the friction of sliding
surfaces that are used to move components of microelectromechanical
systems (MEMS). In one aspect of this exemplary embodiment, an
electrodeposit formed between the electrodes on the solid
electrolyte solution layer may increase the frictional and
stictional focus of the surface of the solid electrolyte solution
layer. Further, in another aspect of this exemplary embodiment, the
programmable surface control device may provide a continually
renewable metallized surface by applying a sufficient bias between
electrodes where a part of a MEMS device, such as a mechanical
oscillator, for example, wears down an electrodeposit or metallized
surface. The programmable surface control device of this exemplary
embodiment may also be used to provide a renewable metallized
surface in MEMS which include electric relays or any other
functions which are capable of wearing down a metallized
surface.
[0011] The present invention is also directed to a method for
making a programmable surface control device which includes the
steps of forming a solid electrolyte solution layer containing a
conductive material and forming a pair of electrodes on the surface
of the solid electrolyte solution layer where one electrode
includes the same type of conductive material as the solid
electrolyte solution layer. The programmable surface control device
is controlled by applying a voltage between the pair of electrodes
to create or dissolve an electrodeposit which, as a result, changes
the surface characteristics and mass distributions of the device.
In one aspect of this exemplary method of the invention, an
electrodeposit is created which alters the surface tension of the
solid electrolyte solution layer thereby increasing the contact
angle of the electrodeposit with the solution layer and making the
solution layer more hydrophobic. In another aspect of this
exemplary method, the electrodeposit increases the friction of the
surface of the solid electrolyte solution layer. In yet another
aspect of this exemplary method, multiple programmable surface
control devices are formed on a material surface and electrical
means are used to control the distribution of liquid on the
material surface.
[0012] In another exemplary embodiment of the present invention, a
method for controlling a microfluidic system is presented which
includes forming the programmable surface control device as
described above in the walls of a microchannel.
[0013] A method for creating a liquid microlens is also
contemplated by the present invention and includes the step of
disposing a liquid droplet on the surface of the solid electrolyte
solution layer formed in accordance with the method for making a
programmable surface control device described above. The shape and
focal length of the microlens is controlled by creating an
electrodeposit on the solid electrolyte solution layer with voltage
applied to the electrodes.
[0014] Still other methods of the present invention include a
method for controlling components of MEMS devices by making
programmably controlled surfaces on which to operate the components
and a method for providing a continually renewable metallized
surface using the programmable surface control device of the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] A more complete understanding of the present invention may
be derived by referring to the detailed description and claims,
considered in connection with the figures, wherein like reference
numerals refer to similar elements throughout the figures, and:
[0016] FIG. 1 is a cross-sectional illustration of an exemplary
embodiment of a programmable surface control device in accordance
with the present invention;
[0017] FIG. 2 is a top plan view of a device with a surface having
multiple controllable sample sites in accordance with another
exemplary embodiment of the present invention;
[0018] FIG. 3 is a perspective view of a microfluidic chip having a
programmable microfluidic system in accordance with another
exemplary embodiment of the present invention;
[0019] FIG. 4 is a cross-sectional view taken along line 4-4 of
FIG. 3;
[0020] FIG. 5 is the cross-sectional view shown in FIG. 4 showing a
fluid contained in the microchannel;
[0021] FIG. 6 is the cross-sectional view shown in FIG. 5 with a
voltage applied across the electrodes contained in the walls of the
microchannel;
[0022] FIG. 7 is a cross-sectional view of a programmable surface
control device in accordance with another exemplary embodiment of
the device; and
[0023] FIG. 8 is a cross-sectional view of the programmable surface
control device shown in FIG. 7 with a voltage applied across the
electrodes of the device.
DETAILED DESCRIPTION
[0024] The present invention generally relates to PMC technology
which is based on the electrodeposition of metal and/or metal ions
from a solid solution upon application of a suitable electric
field. More specifically, the present invention relates to
programmable surface control devices whose physical features, such
as surface characteristics and mass distribution, are controlled by
the presence or absence of a metallic electrodeposit upon
application of a bias.
[0025] FIG. 1 illustrates a cross-sectional view of an exemplary
embodiment of a programmable surface control device 5 in accordance
with the present invention. Device 5 includes electrodes 10 and 20
formed on a surface of a layer of a solid electrolyte solution 30.
Solid electrolyte solution layer 30 is formed from a material that
conducts ions upon application of a sufficient voltage. Suitable
materials for solid electrolyte solution layer 30 include
chalcogenide glasses with dissolved conductive materials, such as
dissolved metals and/or metal ions. The concentration of the metal
in the chalcogenide glasses is typically on the order of many tens
of atomic percent. In accordance with the present invention,
exemplary chalcogenide glasses with dissolved metal include solid
solutions of As.sub.xS.sub.1-x--Ag, Ge.sub.xSe.sub.1-x--Ag,
Ge.sub.xS.sub.1-x--Ag, As.sub.xS.sub.1-x--Cu,
Ge.sub.xSe.sub.1-x--Cu, Ge.sub.xS.sub.1-x--Cu, other chalcogenide
materials which include silver, copper, or zinc, combinations of
these materials, and the like.
[0026] Electrodes 10 and 20 include an anode having an oxidizable
form of the metal dissolved in the chalcogenide glass and an inert
cathode. When a voltage is applied between electrodes 10 and 20,
the positively charged metal ions will migrate toward the cathode
region. Once a sufficient bias is applied, the metal ions will form
a stable metallic electrodeposit 40 that may extend across the
surface of the solid electrolyte solution layer 30 from the cathode
to the anode. The magnitude of the sufficiently bias will depend
upon the materials used, the series resistances involved, and the
geometry of the device. The applied bias is typically within a
range of about 200 mV to 20V, but it will be appreciated by those
skilled in the art that any bias suitable for forming stable
metallic electrodeposit 40 may be used. The morphology of the
resulting metallic electrodeposit will depend, in part, on the
applied bias and on the total charge of the metal ions that are
deposited.
[0027] Metallic electrodeposit 40 can significantly alter the
surface characteristics and mass distribution of programmable
surface control device 5. In one exemplary embodiment of the
present invention, electrodeposit 40 may increase the contact angle
of the surface of solid electrolyte solution layer 30 thereby
resulting in a more hydrophobic surface. For example, silver
electrodeposition on the surface of a programmable surface control
device in which silver is dissolved in a germanium selenide glass
may alter the surface tension of the surface of the glass so that
the contact angle may increase by 30 degrees or more, making the
surface of the glass significantly more hydrophobic. In another
exemplary embodiment of the present invention, the presence of the
electrodeposit may increase the friction of the surface of the
glass. Reversing the applied bias will cause the electrodissolution
of the electrodeposit, thereby returning the programmable surface
control device to its original surface state. In a further
exemplary embodiment of the present invention, metal ions can be
manipulated towards either the cathode or the anode by supplying a
sufficient bias to the programmable surface control device.
Accordingly, mass distribution within the programmable surface
control device can be controlled.
[0028] Programmable surface control technology may be utilized in a
variety of applications that may benefit from the
electromanipulation of the surface tension, surface friction, and
mass distribution of programmable surface control devices.
[0029] 1. Droplet Control and Microdams
[0030] A variety of applications such as immunoassay array
applications, other forms of small sample chemical analyses
applications, and even various printing applications, for example,
require the control of small quantities of liquids, typically in
the form of droplets on surfaces. Since the metallic electrodeposit
of a programmable surface control device may be used to control
surface tension, and therefore surface wetting, of the surface of a
solid electrolyte solution layer of the programmable surface
control device, it is possible to control liquid distribution on a
surface that contains an arrangement of such devices using
electrical means. The programmable surface control devices could be
organized individually on a hydrophobic surface for the selective
trapping of single droplets or in arrays to form multiple
controllable sample sites. In the case where multiple controllable
sample sites are formed, the sites where the electrodeposit is
present would have a weaker hold on the sample liquid than those
sites without the electrodeposit thereby allowing the droplets to
be preferentially held at the latter sites.
[0031] Programmable surface control devices may comprise a variety
of configurations, including dots, elongated structures, or other
complex two-dimensional shapes. Moreover, various geometries can be
used to act as surface tension dams to control fluid distribution
on a hydrophilic surface. In this case, the growth of the
electrodeposit, which results in a relatively hydrophobic surface,
could be used to confine or exclude liquid from a region of the
surface.
[0032] A top plan view of a device 105 with a surface 130 having
multiple controllable sample sites in accordance with another
exemplary embodiment of the present invention is shown in FIG. 2.
Electrodes 110 and 120 are formed on surface 130 which comprises a
chalcogenide glass with a dissolved metal. One of electrodes 110
and 120 comprises an anode having an oxidizable form of the same
metal that is dissolved in the chalcogenide glass and the other
electrode comprises an inert cathode. When a voltage is applied to
electrodes 110 and 120, an electrodeposit 140 is formed on surface
130 between electrodes 110 and 120 thereby creating a hydrophobic
surface which can be used to confine sample liquid to sample sites
145.
[0033] 2. Microvalves
[0034] Microfluidic systems are systems in which fluids are made to
flow by capillary action in micro-scale channels and are typically
used in biochemical analyses applications. Programmable surface
control devices like those of the present invention may be used to
control the fluid flow in such microfluidic systems.
[0035] FIG. 3 is a perspective view of a microfluidic chip 202
having a programmable microfluidic system 204 in accordance with
another exemplary embodiment of the present invention. In this
exemplary embodiment, a programmable surface control device 205 as
previously described with reference to FIG. 1 is disposed within
the walls 206 of a microchannel 207 comprising part of the
microfluidic system 204 as shown in FIG. 4. FIG. 4 is a
cross-sectional view taken along lines 4-4 of FIG. 3. Device 205
includes a pair of electrodes 210 and 220 formed on a solid
electrolyte solution layer 230.
[0036] FIG. 5 illustrates the cross-sectional view of FIG. 4 with a
fluid 232 contained within microchannel 207. When no voltage is
applied to electrodes 210 and 220, a surface of fluid 232 forms
about a ninety degree contact angle with respect to wall 206 of
microchannel 207 as shown by angle AB. However, when voltage is
applied to electrodes 210 and 220, an electrodeposit 240 is formed
on a surface of layer 230 as shown in FIG. 6 thereby making the
surface of layer 230 more hydrophobic. Making the surface of layer
230 more hydrophobic results in increasing the contact angle of
fluid 232 with wall 206 of microchannel 207 as shown by angle CD.
Even a minimal contact angle increase can be sufficient to stem or
retrain the flow of fluid 232 through microchannel 207.
[0037] Accordingly, disposing a programmable surface control device
in accordance with the present invention within the walls of a
microchannel can function to control fluid flow within the
microchannel and, as a result, fluid flow within a microfluidic
system that includes the microchannel. In one exemplary embodiment
of the invention, the formation of a silver electrodeposit on a
germanium selenide-silver glass may produce a contact angle change
that is typically larger than 10 degrees thereby producing a
microchannel liquid valving effect.
[0038] 3. Microlens Control
[0039] Programmable surface control devices of the present
invention may also be used to create a liquid microlens. Liquid
droplets can function as excellent natural lenses and can be used
for a wide variety of temporary imaging and/or focusing/coupling
applications. The shape of a liquid microlens is typically
determined by the liquid used and the hydrophobicity of the surface
upon which the liquid is disposed. Since the presence of an
electrodeposit at the surface of a solid electrolyte solution layer
of a programmable surface control device can significantly change
the contact angle of liquid droplets disposed on the surface, the
shape of the liquid droplets can be manipulated by the presence of
the electrodeposit. Therefore, since the hydrophobicity of the
surface of the programmable surface control device can be altered
electrically, a liquid microlens with an electrically controllable
shape and focal length can be created.
[0040] An exemplary embodiment of such a device 305 is shown in
FIGS. 7 and 8. Device 305 includes a pair of electrodes 310 and 320
formed on a surface of a solid electrolyte solution layer 330 which
may comprise a chalcogenide glass containing a dissolved metal. A
liquid droplet 350 is disposed on the surface of layer 330 of
device 305. By applying a voltage to electrodes 310 and 320 of
device 305, the shape of liquid droplet 350 can be manipulated to
provide a desired shape and focal length as shown in FIG. 8. When
voltage is applied to electrodes 310 and 320 and a sufficient bias
is achieved, an electrodeposit 340 is formed across the surface of
layer 330 between electrodes 310 and 320. Electrodeposit 340 makes
the surface of layer 330 more hydrophobic thereby altering the
shape and focal length of liquid droplet 350.
[0041] The shape and focal length of liquid droplets can be
manipulated to provide a desired shape and focal length by applying
voltage to the electrodes of the programmable surface control
device. Moreover, a polymer film 360 that does not adversely effect
the desired focal length of the liquid droplets can be applied to
the liquid droplets to prevent their evaporation.
[0042] 4. Friction Control
[0043] A variety of MEMS have parts that move in a near vacuum or
in a damping fluid. However, a growing number of MEMS components
are configured to operate using sliding surfaces. The programmable
surface control devices of the present invention may be used to
control the friction of such sliding surfaces. For example, silver
electrodeposition on the surface of a programmable surface control
device in which silver is dissolved in a germanium selenide glass
may increase the frictional and stictional focus of the surface of
the glass.
[0044] In addition, the programmable surface control device of the
present invention may be used to provide a continually renewable
metallized surface. For example, referring back to FIG. 1, as
electrodeposit 40 is subjected to frictional forces from a part of
a MEMS device, such as a mechanical oscillator (not shown) which
oscillates against electrodeposit 40 between electrodes 10 and 20,
metal ions from the anode and the solid electrolyte solution will
migrate toward the cathode, effectively renewing the electrodeposit
40 and compensating for wear of electrodeposit 40. The programmable
surface control device may also be used to provide a renewable
metallized surface in a variety of other applications such as, for
example, in electric relays and the like.
[0045] Although the present invention is set forth herein in the
context of the appended drawing figures, it should be appreciated
that the invention is not limited to the specific form shown. For
example, while the programmable surface control structure is
conveniently described above in connection with controlling
microfluids and the friction of recurrently used surfaces, the
invention is not so limited. For example, the structure of the
present invention may be suitably employed as a programmable memory
device or as programmable active or passive devices within a
microelectronic circuit. Various other modifications, variations,
and enhancements in the design and arrangement of the method and
devices set forth herein may be made without departing from the
present invention as set forth in the appended claims.
* * * * *